In an existing long term evolution (LTE) system, a subframe has duration of 1 millisecond (ms), and each subframe includes 14 time-domain symbols. Usually, in the LTE system, uplink control information may be transmitted in an uplink subframe by using a physical uplink control channel (PUCCH). An existing PUCCH occupies 14 time-domain symbols.
To support technologies such as dynamic scheduling, downlink multiple-input multiple-output (MIMO) transmission, and hybrid automatic repeat request, a terminal device needs to feed back, to a base station, uplink control information (UCI), including channel state information CSI, a hybrid automatic repeat request-acknowledgment HARQ-ACK, a scheduling request (SR), and the like. The hybrid automatic repeat request-acknowledgment may be simply referred to as an acknowledgment (ACK)/negative acknowledgment (NACK).
In a future evolved LTE system, a TTI (Transmission Time Interval) may be reduced to reduce a service latency, that is, the transmission time interval TTI may not be one subframe, for example, may include less than seven time-domain symbols. When the TTI is reduced, an uplink control channel for uplink control information transmission, such as a physical uplink control channel PUCCH, may occupy less than 14 symbols in a time domain.
In addition, in a future evolved LTE TDD system, a new subframe type is introduced. A subframe of the new subframe type includes a symbol used for downlink transmission, a symbol used for uplink transmission, and a guard period GP. Uplink control information may be transmitted on the symbol used for uplink transmission in the subframe of the new subframe type. For example, in the future evolved LTE system, a subframe type shown in FIG. 1 may be introduced. A subframe of the subframe type shown in FIG. 1 includes 11 symbols used for downlink transmission, a guard period (GP) with duration of one symbol, and two symbols used for uplink transmission. The uplink control information may be transmitted on the two symbols used for uplink transmission.
The existing physical uplink control channel PUCCH needs to occupy 14 symbols in the time domain, and is inapplicable to uplink control information transmission in a short-TTI scenario or in a subframe of the new subframe type. Therefore, a new uplink control channel structure needs to be designed for uplink control information transmission.